Pallet handler for concrete block machines



July 28, 1959 P. M. THOMAS ET AL PALLET HANDLER FOR CONCRETE BLOCK MACHINES Filed Jan. 7, 1958 8 Sheets-Sheet l INVENTORS.

m w m a July 28, 1959' P. M. THOMAS ET AL 2,

PALLET HANDLER FOR CONCRETE BLOCK MACHINES Filed Jan. '7, @958 8 Sheets-Sheet 2 July 28, 1959 P. M. THOMAS ETAL 2,395,800

PALLET HANDLER FOR CONCRETE BLOCK MACHINES Filed Jan. 7, 1958 8 Sheets-Sheet 5 Eii 40 INVENTORS.

July 28, 1959 P. M. THOMAS ET AL 2,896,800

PALLET HANDLER FOR CONCRETE BLOCK MACHINES Filed Jan. 7,, 1958 8 Sheets-Sheet'4 INVENTORS. PAUL IV. 7WOHfl5-mva- AIM/FENCE 9% R47 WF/Gf/l' July 28 1959 P. M. THOMAS ET AL 2,896,300

, PALLET HANDLER FOR CONCRETE BLOCK MACHINES Filed Jan. 7, 1958 8 Sheets-Sheet 5 23 .303 W A 95 189 Ml- 297 v 1 mm y 10 INVENTORIS. 7

11.7 TOENEX' A July 28, 1959 P. M. THOMAS ET AL 2,896,800

PALLET HANDLER FOR. CONCRETE BLOCK MACHINES Filed Jan. 7, 1958 8 Sheets-Sheet 6 July 28, 1959 P; M. THOMAS ET AL PALLET HANDLER FOR CONCRETE BLOCK MACHINES Filed Jan. 7, 1958 s Sheets-Sheet 7 5M mm H w wr u g m w 4 y 1959 P. M. THOMAS ET AL 2,896,800

PALLET HANDLER FOR CONCRETE BLOCK MACHINES Filed Jan. 7, 1958 s Sheets-Sheet 8 21- 133 INVENTORS.

ZQ MM ATTORNEX zza United States Patent PALLET HANDLER FOR CONCRETE BLOCK MACHINES Paul M. Thomas and Lawrence W. Pat Wright, Phoenix, Ariz., assignors to Builders Equipment Company, Phoenix, Ariz., a corporation of Arizona Application January 7, 1958, Serial No. 707,606

6 Claims. (Cl. 214-164) This invention pertains to improvements in pallet handlers for manipulating concrete blocks on pallets from the block making machine to the pallet racks and returning the empty pallets from the racks to the block making machines. More particularly this invention is directed to a control system and apparatus for operating a pallet handler in an automatic manner.

One of the particular objects of this invention is to provide an improved control mechanism for a pallet handler such as shown in Patent 2,803,356 but which automatically and sequentially removes empty pallets from and presents loaded pallets in a pallet rack including means for automatically laterally positioning the pallets relative to the pallet rack slides for accurate and easy entrance of the loaded pallets in the rack without special care being required as to the position or exact dimensions of the racks.

Still another object of this invention is to provide an automatic pallet handler which is capable of presenting loaded pallets into the rack in such a way that it returns the loaded pallets to the exact center of the opening where it just removed an empty pallet.

Another object is to provide an automatic pallet handler wherein a novel probe device finds and determines the center of the guideways in the rack when it picks up the empty pallet to be returned to the block making machine so that when the handler returns with the loaded pallet it will be accurately inserted into the pallet rack without attention or skill upon the part of the operator.

Still another object of this invention is to provide in conjunction with such a machine means for automatically probing the center line lateral position of the rack slot to receive a loaded pallet and to precondition the handler as it travels from the rack to the block machine with an empty pallet so that as the handler returns with the loaded pallet it will exactly insert the loaded pallet in proper centered position in the position in the rack where it had just previously picked up the empty pallet.

It is also a further object in connection with the aforementioned apparatus and operation to provide automatic control apparatus for the handler so it may pick up and deposit pallets in the pallet rack at various levels of the shelves in an automatic successive manner while performing the aforementioned probing and centering function at each level of operation.

Further features and advantages of this invention will appear from a detailed description of the drawings in which:

Fig. 1 is a fragmentary plan view of a pallet handler incorporating the features of this invention.

Fig. 1a is an enlarged end view of the block making machine conveyors indicated by the line la-la in Fig. 1.

Fig. 2 is a fragmentary right hand side elevation of the pallet handler indicated by the line 2-2 in Fig. 1.

Fig. 3 is a section on the line 3-3 of Fig. 2.

Fig. 4 is a section on the line 4-4 of Fig. 2..

Fig. 5 is a section on the line 5-5 of Fig. 4.

2,896,800 Patented July 28, 1959 Y the line -10 of Fig. 8.

Fig. 11 is an enlarged fragmentary sectional view on the line 11-11 of Fig. 10.

Fig. 12 is an enlarged fragmentary sectional view on the line 12-12 of Fig. 2.

Fig. 13 is an enlarged fragmentary sectional view on the line 13-13 of Fig. 12.

Fig. 14 is an enlarged fragmentary sectional view on the line 14-14 of Fig. 12.

Fig. 15 is a diagrammatic view showing the pallet handler platen entering the pallet rack to pick up empty pallets.

Fig. 15a is an enlarged fragmentary section on the line 15a-15a of Fig. 15.

Fig. 16 is a view similar to Fig. 15 but showing the device probing for centerline position of the rack guideways.

Fig. 16a is an enlarged section on the line 16a-16a of Fig. 16.

Fig. 17 is a view showing the pallet handler with empty pallets swung to deliver the empty pallet to the block making machine conveyors.

Fig. 18 is a view showing the pallet handler discharging empty pallets and picking up loaded pallets.

Fig. 18a is an enlarged fragmentary section on the line lilo-18a of Fig. 18.

Fig. 19 is a view showing the pallet handler swung to position to insert the loaded pallets intothe pallet rack.

Fig. 19a is an enlarged sectional view on the line 1901-1941 of Fig. 19.

Fig. 2.0 shows the pallet handler after depositing loaded pallets in the rack and probing and pick up the next below empty pallets.

Fig. 20a is an enlarged fragmentary section on line 20a-20a of Fig. 20.

Fig. 21 is a wiring diagram of the operating and control apparatus of the pallet handler.

As an example of one embodiment of this invention there is shown, Figs. 1, 2, 3 and 4, a pallet handler for a concrete block machine comprising a main frame 25 including a pair of spaced horizontal rails 26 and 27 supported on suitable upright standards 28 and 29 above the ground level 30. A carriage indicated generally at 31 comprising the transverse side rail members 32 and 33 and the end members 34 and 35 rigidly fixed to the outer ends of the members 32 and 33 is transportably carried on suitable rollers 36a carried on shafts 36 and 37 suitably journaled in the frame 31 and running along on the rails 26 and 27. A suitable reversible electric motor 38 mounted on the carriage 31 is energized for one direction of rotation by closing power contacts 225 by energizing relay coil 224 and for opposite rotation by energizing relay coil 305 to close power contacts 306 and has a drive shaft 39 and a pulley 40 fixed thereon over which operates the belt 41 which in turn operates over the pulley 42 fixed to the shaft 37 so that the motor 38 may be energized to traverse the carriage 31 to the right and left, Figs. 1 and 2, on the frame 25 of the machine.

A cross movement frame indicated generally at 43 comprises the side members 44 and 45 and connecting pieces 46 and 47 transportably carried on rollers 46 journaled on suitable shafts 47 fixed to the cross movement frame 43. A fluid pressure cylinder 48 is fixed to the cross movement frame 43 and has a double end piston rod 49 with its outer ends suitably fixed to the end members 34 and 35 of the carriage 31. Fluid pressure for the actuating cylinder 48 is derived from a suitable pressure line 50, Fig. 21, connected to the electrically operated reversing-control valve 51 from which the co-ntrol'lines '52 and 53 connect-to the cylinder 48, so that by appropriately energizingthevalve -51-the cross movement frame 43 may be traversed-forward and-back on the carriage 31 at right angles to the travel ofthe carriage on the mainframe ZS.

A vertically disposed rack shaft S4'is-journaled against axial movemet in the cross movement frame 43 andis rocked back and forth by a fluid pressure cylinder 55 fixed on the cross movement frame-43 and having a piston rod 56 to which is fixed a rack' 57 which is inmesh with the rackpinion 58 fixed to therack shaft 54. Fluid. pressure for operating the cylinder'55 is controlled by the electrically operated control valve 59, Fig. 21, to which is connected the pressure supply line "50 and-tho control supply lines-60 and 61 which in turn are connected to the cylinder 55, so that by properly'energizing' the valve 59 the rack shaft 54 may be rotated clockwise or counterclockwise, 'Fig. '1, as required.

Fixed to the lower end of the rack shaft 54' by mappropriate clampnut means-62 is the topplate 63 of'the pallet handler frame indicated "generally 'at-64'comprising the downwardly extending guide members 65,66, 67 and 68 fixed at their upper-ends'to the top plate 63, the lower ends of the guide members being held together by a suitable tie plate69'fixed thereto. Mounted to ride vertically up and 'downon the "guide members 65, 66, 67 and 68 is the pallet supporting platen indicated generally at 70 comprising the main horizontal-member 71, the vertical rear members 72 and 73 and-the diagonal members '74 to which are journaledsuitable, guide rollers 75 so that the platen 70 may move vertically'up and down on the guidewaysof the pallet handlerfframe.

An up and down movement reversible motor'76 is fixed on the plate 77 in turn fixed to the pallet handler frame 64 and drives a suitable reduction unit 78 fixed on the plate 77 which'is adapted to-wind 'up or unwind the lifting'chain 79 whichpasses down over the idler sprocket 80 journaled in thepallet handler frame 64'and has its lower'end fixedto the'member 71 of the platen 70 so that by appropriately energizing the up and down motor '76 the platen 70 may be raised and lowered on the pallet handler frame 64.

The top surface 81 'of the horizontal member 71 of the platen 70 is'made flat to engage under'and support by gravity the steel pallets 82 while inside the platen horizontal member 71 and fixed electromagnets 83 and 84 having their lower active faces 85 adapted to engage the upper surfaces'of the pallets 82, when empty, by magnetic force.

The pallet rack indicated generally at '86 from which empty pallets 82 are'to be removed and delivered to the block making machine and which received loaded pallets contain the cement'blocks 104 from the block making machine as performed by the pallet handler, comprise upright standards 87, 88 and 89 which are tied'together at the bottom by the horizontal members 90 and at the top by the horizontal members 91. Fixed to the upright standards 87, 88 and 89 are the L-shaped guide rails 92 having'facing horizontal surfaces 93 which support the under side of the pallets adjacent the outeredges 94 of the pallets 82 and the vertically disposed facing surfaces 95a spaced just slightly further apart than the distance between'the outer edges 94 of the pallets, see Fig. 15a.

The concrete block making machine (not shown) has the usual receiving conveyor '95 to receive theempty pallets 82 as they are dropped'on'the 'conveyor'belt 96 when holding magnets'83 and84 are deenergized. Above the receiving conveyor 95 isthe discharge conveyor 97 having verticallydisposedguide'surfaces'98 to keep'the loaded pallets $2.0m the center line 99 as the loaded pallets are'delivered'from' th'eblock making machine out 4 over the top-surface 81 of theplaten for pick-up. and delivery to the pallet rack 86, the center line 100 of the platen 70 coinciding with the center line 99 of the delivering conveyor 97 at the time the pallet picks up the loaded pallets. The receiving conveyor 97 is not critical as to the deposit of empty-pallets so that the center line 101 of .theempty palletsneed-not-be coincident with the centerline99as' they aredropped on the receiving conveyor. It is important to pick up the loaded pallets so that thecenter'line 102 of the "loaded pallets coincide with center line 100- of .the :platenwhen the platen picks up the loaded pallets and'delivers them to the pallet racks, this being accomplished by accurately andpositively stopping the movement to the left, Figs. 1 and 2, of the carriage 31.

A real problem, however, presents itself in inserting the loaded pallets in between the surfaces 93 of the L- shaped guide rails of the pallets racks since a definite fixed stoppe'dposition of travel to'the right, Fig' 4, for the cross movement framefid cannot'be usedbecauseit has been found in'actual practice that:the'-pallet'racks 7 cannot be precisely positioned with the center'line 103 of each vertical-racknow-in the-sameposition every time they-are presented tothe-pallet handler machine because the fork lift trucks used to handle the pallet-racks-cannot be spotted'that accurately. Also, the "dimensions of the racks vary due'to fabricationtechniques so'that a definite stop engaging the outsidesurfaces-oftheracks is of-noavail to provide accurate positioning; "A still more pressing problem is the variationin spacing-between the vertically disposed'facingsurfaces 9500f the a guide rails 92 due to fabrication inaccuracies manntortionof the racks during long use and thefurtherproblem of the racks becoming bent and-skewedsothat the surfaces 95a do not necessarily present themselves in symmetrical "alignment'with'the center lines 103 ofthe vertical rack rows, Fig. 3. Also, variation in 'vertical spacing of the'surfaces' 93 ofthe guideways brought'about by the matters recited above lead-to 'difiiculticsjin the vertical positioning of the pallet "handler frame "and platen.

The above problemsaresolved-automatically by the instant device whereinall of'themovements of thepallet handler, particularly the cross-and vertical movements, are determined'by an electric probing'and control apparatus sensing the actual-position of emptypailets in the pallet racks as the basic control for performing'the pallet handling'operations. To this'end the machine is arranged to operate as "follows, referring particularlyto Fig. 21: Assuming'the'pallet handler is positioned with its platen at the receiving and discharge conveyors'95 and 97 of the block making machine, Figs. la and '4, the movement of the-loaded pallets intthe direction indicated by the arrow'lllS by'the discharge conveyor 97 cause the loaded pallet to actuate the limit switch "L8 4 connected to control current supply lead L2 connected toone terminal of the secondary Winding '1'11 of the control transformerllZ having a primary winding1l'3 connected to the'lea'ds 114 and 115 connecteditoth'e threephase alternating current power supply leads I16, 117 and 118 through the main disconnect switch'119. The other end of limit switch LS-4 is connectedto relay coil CR-4 the other end of which is connected totheother control current lead L1 in turn connected to the other'terminal 122 of the secondary winding 111. This energizes relay coil CR-4 closing its normally open contact 123, and since normally closed contact 124 of relay1CR-5 are closed as well as the normally closed extreme upper limit switch LS-6 and hand safety switchl'Z'l' is closed, the relay coil Up is energized closing power contacts'129 to energize motor/76 to raise platen.70 as described. The platen raisesapproxirnately s-ix inches-'until'limit switch LS-S carried. on' the platen andengag ing a dogon frame 64 is actuated, which energizes r'elay'CR'5 stopping upward movementby'opening normally closed 'contactl24.

This procedure is followed for all shelves onthe pal-Y let rack from the ground up to limit switch LS-S. On shelves higher than the position of limit switch LS-S control relay CR-14 would not be energized. A limit switch LS-15, Figs. and 7, is mounted on a slide member 108 arranged to slide vertically on the guide rod 109 fixed at its ends on the top plate 63 and tie plate 69 of the pallet handler frame 64, an electro-magnet 120 being adapted when energized to lock the slide member 108 to the guide rod 109 and when deenergized to allow the slide 108 and limit switch LS-15 to drop downwardly so that abutment lug 121 on the slide member 108 is stopped against abutment lug 125 fixed on the pallet handler frame 64. Limit switchis set to. a certain shelf height when the platen engages the top of an empty pallet in the pallet rack at which instant the electro-magnet 120 is energized to hold slide member 108 on the guide rod 109. With LS-15 set for a certain shelf height, the normally closed contacts 126 would bypass CR-S and the platen 70 would raise until LS-15 is actuated opening its normally closed contacts when the dog 128 on the pallet handler frame 64 engages the operating arm 130 of thelimit switch LS-IS. l Y

Regardless of the shelf level, when LS-S has been actuated and CR*5 energized, the normally open contacts 131 energizes CR-23 and normally open contacts 132 close to operate solenoid 133 of control valve 59 to turn pallet handler frame 64 clockwise, Fig. 1, until it hits a suitable mechanical stop (not shown) with the platen pointed in the direction of the pallet rack 86 as shown in Figs. 1 and 19. The normally open contacts 134 of CR-5 energizes CR-22 to close contacts 135 so as to energize solenoid 136 of control valve 51 to cause the frame 43 to move backwards away from the block making machine conveyors 95 and 97 until a suitable automatically adjustable mechanical stop, to be subsequently described, is engaged and at this time a limit switch LS-8 is actuated to energize CR-8 with the result that if the shelf in the rack about to be filled is lower than LS-S, the platen can now be lowered to proper height. The contact 137 is closed because CR-S is held in by its own locking contacts; contact 133 of CR-8 is closed when carriage 31 is in rear position; contact 139 is closed because on the lower shelves LS-14 is actuated; normally closed contact 140, this being limit switch set for correct height; contact 141 of CR- is closed, CR-10 actuated when platen is on top of empty pallets; contact 142 of CR-17 is closed, platen not on extreme down limit; and hand control safety switch 127 is closed. The platen then drops until connect shelf height is reached whereupon LS-16, Figs. 5, 6 and 7, has its control arm 143 engaged by dog 144 fixed on the pallet handler frame 64 to open itsnorrnally closed points, the limit switch LS-16 being mounted on a slide member 145 sliding up and down on the guide rod 146 fixed at its ends to the top plate 63 and tie plate 69 of the pallet handler frame 64. An electro-magnet 147 is fixed to theslide member 145 and when energized locks the frame 145 to the guide rod 146 and when deenergized allows free sliding movement of the frame on the guide rod. An abutment lug 143 fixed on the platen engages the lower surface of the lug 149 on the slide member 145 to control the up and down movement and position of the limit switch LS-16 from the movement of the platen.

The carriage 3 1 and platen 70 move to the right, Figs. 1, 2 and 20 since LS-19 closed, 90 interlock to the right; LS-16 closed for correct shelf height on lower shelves; if machine is filling upper shelves LS-15 would be closed; contact 150 of CR-S closed with carriage 31 in extreme rear position, Fig. 19; contact 151 of CR-9 closed stopping carriage movement to right; contact 152 of (ZR-10 not opened until empty pallets engaged by underside of platen; and contact 153 of CR-17 only open at end of filling rack with hand safety switch 127 closed. The carriage 31 and platen with loaded pallets then moves toward rack;. Fig..20, until is-a is actuated energizingv CR-9 by opening contact 151 of CR-9.

The adjustable stop mechanism for limiting outward travel of theframe 43 away .fromthe block machine conveyors, for, positioning theplaten relative to the center line 103 of the pallet rack comprises the apparatus shown particularly, in Figs. 12, 13 and 14. A rotatable nut 154 is suitably journaled against axial movement in the bearing 'housing- 155 rigidly fixed to the carriage 31 of the machine and operates over an axially adjustable screw 156 having a squared outer end axially slidable but held against rotation in the guide sleeve 158 secured by the bracket 159 to the carriage 31. A reversible adjusting screw motor 160 fixed on the carriage 31 is connected through a chain 161 to a sprocket16 2 fixed to the nut 154 so that by. suitably energizing the motor 160 the screwl156 and squared outer end may be positioned relative to the carriage 31. An abutment surface 163 on the outer end of the squared outer end 157 is adapted to engage and position the frame 43 in outer cross movement asdictated by the energizing of the motor 160.

When-contact. 164 of vCR--9 closes and if the adjusting screw motor 160 is not adjusting the screw 156 by.contact 165 being broken, then the platen drops until stopped mechanically engagement with the topsurface of the empty pallet, Fig. 20, and electrically by actuation of LS.-10 which energizes CR-10 and breaks down circuit by opening contact 141. When platen drops down to deposit full pallet on surfaces 93 of the rack and to engage the top of an empty pallet the energizing of CR-9, which drops the platen, also opens contact 166 and causes electro-magnet 147 to deenergize to drop LS-16 with the platen. When the platen stops on top of the next empty pallet, LS-10 is actuated, CR-lt) energized, closing contact 167 of CR-10; contact 168 of CR-17 is closed; contact 169 of CR-17- is closed and the circuit to the top electro-magnet 147 is again made up locking frame 145 and LS-16 to the guide rod 146. This sequence is repeated each timeuntil the shelves have been filled down to the level of LS-5. At this point electro-magnet 147 and guide frame 145 actuates 160 which energizes CR-14 opening contact 169 thereby breaking the circuit for the top magnet 147. At the same time contact 170 of CR-14 closes, making all energizations and de-energizations pertinent to the bottom electro-magnet 120.

A probing device engaging the vertically disposed facing surfaces 95a95a of the guide rails 92 of pallet racks, Figs. 15a and 16a is utilized to sense the degree of misalignment or offset of the axis 100 of the platen andthe axis 103 of the pallet rack at the time the platen comes down on top of the empty pallet preparatory to picking up the pallet by the electro-ma'gnets 83 and 84, this sensing action being used to energize motor 160 through power contacts 307 operated by relay coil 308 and power contacts 309 operated by relay 310 to adjust the abutment surface 163 the amount of correction necessary to bring axes 100 and 103 in alignment when the platen returns with a loaded pallet to the same guide rails in the rack from which the empty pallet was picked up. This adjustment-is made during the time the platen is traveling from the rack to the block machine conveyors so that upon return of the cross movement frame 43, the abutment surface 163 of the screw 156 is correctly positioned to stop the frame 43 in accurate alignment with the pallet rack for insertion of the loaded pa et. V

The probing unit comprises a probe box 171 con sisting of the sides 172 and 173, the bottom 174, and the top 175 all of which is rigidly secured to the rear top surface 81 of the platen 70. Slidingly mounted on the top surface 176 of the bottom 174 between the in-. side faces 177a and 177b of the sides 172 and 173 of the probe. box 171.is the pinion plate 178 having an upstandingpin 179 fixed thereintupon which is journale'dthe rack pinion180 which engages a, pair of racks 181 and 182 slidablymounte'cl on'the'top'surface183-;of the pinion:plate"178 andguided against the sidesur'faces 177a and 17717. The rack 182has its outer end '184 projecting through and guided in a suitable opening in the end coverplate 185 fixed to the box 171 while the other rack 181 has its outer end 186 projecting through and guided in a suitable opening in the end cover plate 187 fixed to the'box 171. Probe fingers 188 and .189 are fixed to the ends 186 and 184 of the racks 181 and 182 andhave contact surfaces 190 and 191 adapted'to engage the vertically disposed facing surfaces 95atof the guiderrai-ls 92 of the pallet racks.

Fixed in the upperportion of the probe box 171 are the double actingrfiuidpressure cylinders 192 and 193, cylinder 192'having a piston rod 194 fixed to the probe finger 188 and the cylinder 193 having a piston rod 195 fixed to the probe finger 189 so that by appropriately applying fluid pressure through vthe lines 196 and "197 from the probe control valve 198, Fig. 21, thecylinders 192 and 193 :mavmove the ;.probe .fingers away from each otherv or retract them .toward ,eachtotherlwhile rotating ,the. rack pinion 1180 1 in the process.

f Fixed .to :the bottom of the pinion plate 178, L Fig. l0, is a .rack 199 which engages a gear 200 fixed to the shaft-201 suitably journailed 3 in a hearing .202 in the sidej172 ofthe probe box -171. vAn agnetic clutch 203 connects or disconnects drive from the shaft 201 to the potentiometershaft 204 journaled-in asuitatblehcaring.205 in the support bracket 206 fixed totthe platen 70 and connected to operate thepotentiometerj207. An electrically operated brake208 carried on -the,platen '70 isa'dapted when. appropriately energizedto arrest rotation of the shaft 204 or to release the shaft -for free,rotation. Also 'fixed to the shaft '204'is a sprocket 209,1Figs. '10 and 11, to Whi'chis fixed a link chain;210 ,,operating;over ani'dler sprocket 211 suitably'journaledonfthe platen '70 and'oonnected'to a pull cylinder. 212 lfixedponthe platen 70 and adapted when energized to,r,otate.shaft'204.to return the potentiometer .207 i to centered position.

With the platen resting on top.of.anemptypallet, (ER-10 is energized closing contact 213 gsothatcurrent fiowsthrough contact 214.of,timer relay .T-5, "Fig. ,21, energizing CR-'-20 opening .contactQ215 ,to break circuit to the electric brake'208 on the potentiometenshaftf204. Contact 21.6 of CR-17 closed and contact ,217 now closed so that.the clutch 203 on the potentiometer shaft 204, Fig. '10 is energized connecting ,shaft.20 1 to drive shaft 204. Also solenoid 218 ofjprobecontrol va1ve,.198 is energized to sendfiuidpressurefrom supply 1ine,50 through line 196 to cause cylinders, 19.2 and 193 tomove both probe'fingers 188 and 189 ,outwardly, Fig. 8, .to engage the sides-95a of the rack-guide rails 92. i

.As an example, if the space:between surfaces -95a.o,f therack is at least "26 /z"'wide then limit switch .IlS-JS, Fig. '21, is' actuate'd; thisin turnenergizes time relay T,5 set .for' /z second. It LS18.remains energizedfor /z second'then the.timer relay T- timesoutand contact 214 opens tie-energizing ,CR-120; its contact 217 being broken de-energizes solenoid 2180f probe valve 19,8.to now apply fluid pressure'in linesttoline .197 to,retract the probe fingers 18.8,and189. Also, the clutch 20.3,is deeenergized at this time ,to.,disconnect,-shaft 201.from shaft "204. Contact 215 of CR-20 nowcloses. energizing brake 208. V

If'the space between surfaces 95a of the rack had-been more than 27%" wide theneven though LS-18. hadbeen actuatedit would haveibeen de-actuate'd in lessthan /2 secondand T-5 would nothavelhaditime to-tirne out, consequentlytheplaten would neverhave moved. .However, T 5 did timeout and its contact219. did close. and since :contact 213 is closed. time relay ,T1 is ,energized closing instantaneous contact 220 and closing timeopen contactj221 already closed, contact'222 closed,1 and.contact 223 of'ESR relay closed, safety so that the'Up coil is energized closing power contacts 129' tomomentarily energize motor76liftrpallet slightly frorn raek guideways, whereupon timer relay T 1- times out de-energizingmowr 76. Left solenoid -224-is -energizedclosing power contacts 2 25 ienergizing motor '38 ito=back -out -platen from rackbythe closing ofcontacts of'CR-ll. The'carriage 31,moves awayfromthe pallet rackuntil the-frontend 226 of1the platen 70 clears theyrackythenlimit switch L8 7 is'actuated'and since contact'227;of CR-4 is closed (I;S4 not'actuated, pallets left-in rack),-CR*7 is'energized and is held in by'its ownholding'contact.

As the carriage 331 is still-traveling-away from the pallet rack, CR5 relay held in by its holding contact 229, is now tie-energized, contact230 of CR-10-was previouslyi broken and contact:231 isnow-broken. Con. tact 131 now open, 'de-energizingCR 23, opening'conta'ct 132-de-energizing solenoid "133 of valve :59 for clockwise swinging and contact 232 of CR 23 nowclosed which energizes 'the ;solenoid 233 ;of valve 59 which institutes counter-clockwise swing of the frame 64 by cylinder '55 as described. This counter-clockwiseswinging movement continues for'90 Juntil ,stoppedby suitable mechanical stop means (not shown) 'betweenthe frame 64 and cross movement frame 43, fluid'pressure beingheld in the cylinder to hold the frame"64;against saidmechanical stop sothat the center line of the pallet is aligned with the ,centerline .99 of theblock machine conveyors 95 and'97.

The platen ,nowemoves up ,or down to get to th neutral position .234, Fig. .1a, so .that the platenmay enter'between the conveyors. 'When the pallethan'dler is loading the top shelves, CR-13'is not energized because the top electro-magnet ,147 and frame ,145'has notengaged LE-14 yet. Theplaten now moves down by this circuit. CR-17 contact 235 is closed ,as.recited, CR-12 contact 236 closed, VCR-13 contact 237.closed, CR-4 contact 238. closed, ,CR-10 contact 239 closed, pallets engaged, CR-17 contact 142 bottom limit closed and ,ESR contact 240 closed. Down solenoid DN is energized closing power contact 241 toenergize motor 76 movingplaten down untilneutral position 234, Fig. 1a, is reached,,actuating.LS-12 carriedon platen .and engaging a dog (not shown) on the -frame v64 to open CR,12 contact .236. .Had pallet thandler been filling lower shelves of rack, then top electro-magnet .147 and frame 145 would have actuated LS-14 energizing CR14 closing contact 126, .CR-12 contact 241 would have closed when platen went down to neutral, and. CR+13 becomes energized and CR-13 stays energized by limit switch-L547 also-carried on the :platen and engaged by a dog (not shown) on theframe 64 and by.CR-13 contact 242.

The platen 70 now backing out of rack-wants to raise to neutral. CR- -7 contact 243 is closed,- GR-12 contact 244 closed, CR-13 contact 245 closed, CR10 contact 246 closed, pallet engaged, CR-6 contact 222 closed top limit, and ESR contact 223 closed safety. Platen now raises ,until neutral position 234 is reached actuating limit switch LS-12, CR-17 contact 247 closed, CR-7 contact 248 closed energizing CR-12 opening CR-,12 contact 244 breaking circuit.

The potentiometer 207 is electrically connectedto a slave potentiometer 251 through leads 249 and 250 as shown in Fig. 21, with control power supply lead L1 being connected to lead 249 andlead -L2 gbeing connected to lead 250. The moving arms 252 and 2530f the potentiometers 207 and 251 are each connected by separate leadsv254 and 255 to a conventional commercially available-control device indicated at 256 responsive to the electrical unbalance caused'by the variation in relative angular position of the moving arms 252 and 253 of the potentiometers, suitable control contacts. 257, 258, 259 and 260 being operated froni said control device 256. Referring to Figs. 12, 13 and 14, thepotentiometer 251 is fixed on a bracket 261 fixed to the frame 31 and is connected to a shaft 262 journaled in suitable bearing 263 fixed to the bracket 261, the shaft 262 having a gear 264 fixed to its other end which engages a rack 265 connected to a plate 266 fixed to the squared outer end 157 of the screw 156 so that the slave potentiometer will be adjusted in accordance with the adjustment of the screw 156 by the motor 16,0.

The CR-7 contact 267 and if one of the control relay contacts 257-259 or 258-260 of the control device 256 are actuated because of the positions of the potentiometer arms 252 and 253 because the center line 100 of the platen does not agree with the center line 103 of the rack, then either CR18 or CR-19 will be actuated allowing the motor 160 to rotate the adjusting nut .154 and reposition the stop 163 thereby. CR-18 contact 268 and CR-19 contact 269. are both held in contacts for the adjusting screw motor 160 so that once adjustment starts, removal of actuating power from the original source either CR-7 or CR-17 will not keep nut from finishing adjusting until both potentiometers have been satisfied.

By this time the carriage 31 should have reached. the center of the machine in its travel to the left, Fig. 2, LS-11 is actuated which energizes CR-11 opening CR-ll contact 270 breaking current to relay coil 224, if all interlocks have been satisfied, then cross movement frame moves toward the block machine conveyors 95 and 97, Fig. la, by the following circuit: the limit switch LS-13 closed, 90 interlock; CR-3 contact 271 closed, forward limit switch; CR-12 contact 272 closed, platen in neutral position 234, Fig. la. Approximately ten inches from end of travel of frame 43 LS-2 is actuated energizing CR2 opening contact 273 which de-energizes front magnet 83 and drop first empty pallet on receiving conveyor 95. The second empty pallet is dropped similarly when 1.8-?) is actuated as end of forward travel of frame 43 energizing CR-3 opening its contact 274. Also CR3 contact 271 is opened stopping forward movement of the frame 43, thereby ending one complete cycle.

The above described operation will unload the empty pallets and load full pallets into one complete stall 275 of the pallet rack. In order to shift to and fill other stalls of the rack such as the stall 276, the following operation takes place: The platen 70 enters the rack with the last loaded pallets at the bottom position 277, Fig. 3, having proceeded progressively downwardly through stall 275 as described, and upon complete entry of the platen therein, LS-9 is actuated through push rod 278, Fig. 2, energizing CR-9 and stopping forward movement of the carriage 31. Simultaneously CR-9 contact 164 closes (as described above) and neither CR-18rcontact 165 nor CR-19 contact 279 is open since the adjusting nut 154 and motor 160 are not adjusting. CR- contact 141 will not open since there are no more empty pallets; platen will drop until LS-17 is actuated energizing CR-17 opening contact 142 stopping down travel of platen.

Under these conditions the following takes place: CR-17 contact 216 opens and the brake 208 holding the master potentiometer 205 in place is released. (JR-17 contact 280 closes energizing the solenoid coil 281 of control valve 282 connected to line 283 to the slave potentiometer return cylinder 212 bringing the master potentiometer 205 back into the middle of the travel of its arm 253. CR-17 contact 153 closes furnishing power to potentiometer control box 256 allowing adjusting nut 154 to turn move slave potentiometer 251 to match the master potentiometer which has been returned to the center of its travel.

The carriage 31 now travels away from the rack. ESR hand safety switch 127 is closed, CR-7 contact 282 is closed, CR-17 contact 283 is closed, energizing left coil 224 closing power contacts 225 for lift travel of carriage 31 until platen clears rack and then LS-7 is actuated, since CR-4 contact 227 is closed, CR-7 is energized and CR-7 contact 282 opens stopping left travel.

The platen now raises to extreme top level of travel by the following circuit: CR-7 contact 243 closed, CR-12 contact 244 will not open even on actuation of LS-12 because of CR-17 contact247 in CR-12 circuit, CR-17 contact 284 closed, CR-6 contact 222 closed, hand safety ESR contact 223 closed, so that platen will raise until LS-6 is actuated energizing CR-6 stopping up travel.

The carriage 31 now moves towards the rack with the platen moving back into the rack over the top pallet to pick up and return the top'empty pallet to the block machine so that room is provided for the first loaded pallets. The movement of the carriage 31 toward the rackis accomplished by the following circuit: Normally open limit switch LS-19 closed, interlock, normally open limit switch closed, platen has carried this LS-15 and sliding member 108 to the top with it, CR-14 contact 285 closed, LS-15 at top, therefore cannot actuate LS' 14, CR-8 control 150 closed, cross travel frame 43 in extreme rear position, Fig. l, CR-9 contact 151 closed, extreme right travel limit switch for carriage 31, CR-10 contact 152 closed, no empty pallets attached to platen, CR-17 contact 286 closed, CR-17 dropped out when platen actuated LS-6, hand safety ESR contact 287 blosed.

The carriage 31 travels to the right until LS-9 energizes CR-9 opening contacts .151 breaking circuit stopping right travel. The circuit from here on follows the same pattern as described above. If the adjusting screw 156 is finished adjusting, then platen picks up empty pallets and return to the block machine conveyors to complete the cycle.

On the upper horizontal portion 288 of the probe finger 189, Fig. 9, is fixed the limit switch LS-18 referred to above which has an operating arm 289 having an actuating lug 290 adapted to engage in the annular groove 291 formed in the trip rod292 slidably mounted in bores 293 and 294 in the bracket 295 and 296 fixed to the probe finger 189. Fixed on the outer end of the trip rod 292 is a dog 297 having an abutment surface 298. adapted to engage an abutment surface 299 on the trip lug 300 adjustably fixed to the horizontal surface 301 of the probe finger 188. The trip rod 292 has an abutment surface 302 engaging the bracket 295 and a compression spring 303 abutting the bracket 296 and the washer 304' fixed to the trip rod 292 normally holds the trip rod abutment 302 against the bracket 295 with the actuating lug 290 on the operating arm 289 of 'LS-18 positioned in the groove 291. The purpose of this structure is to provide extreme accuracy in tripping LS-18 at the exact point where the guideways in the rack might be too wide and let a pallet drop through.

There has thus been provided a pallet handler comprising a main frame 25 upon which is reciprocatably mounted a carriage adapted to move to and from the pallet racket and upon which carriage a cross movement frame 43 is mounted to move at right angles to the movement of the carriage 31 to and from the receiving and discharging conveyors and 97 of a block making machine. Suspended from the cross movement frame 43 and adapted to rock through 90 of rotation about a vertical axis thereon is the pallet handler frame 64 upon which is vertically reciprocatable the platen which engages the pallets to be handled.

The pallet racks having stalls for accommodating both empty and loaded pallets include guide rails having vertically disposed facing side surfaces of varying width and location relative to the pallet handling machine. Mounted on the platen are oppositely movable probe fingers adapted to engage these vertically disposed facing side surfaces for sensing their position and spacing which is conveyed to a master potentiometer on the platen. An adjustable stop is mounted on the carriage 31 and engaging the cross movement frame to limit the latters travel on the carriage relative to the position of the pallet rack stalls. Power means are provided to actuate the adjustable stop and a slave potentiometer is connected to the adjustable stop to be actuated thereby in response to the adjustment of the stop. Both potentiometers are connected to a common commercial control device responsive to the information fed to it by the potentiometers to control the operation of the power means for actuating the adjustable stop so as to automatically accurately position the center line of the platen with the center line of the rack stall shelf whenever a loaded pallet is to be inserted therein during the operation of the pallet handler.

While the apparatus herein disclosed and described constitutes a preferred form of the invention, it is also to be understood that the apparatus is capable of mechanical alteration Without departing from the spirit of the invention and that such mechanical arrangement and commercial adaptation as fall within the scope of the appended claims are intended to be included herein.

Having thus fully set forth and described this invention what is claimed and desired to be obtained by United States Letters Patent is:

What is claimed is:

1. In a pallet handler for transferring pallets between a block machine conveyor means and a pallet rack, a frame, a carriage reciprocatably mounted on said frame for movement to and from the pallet rack, a cross movement frame reciprocatably mounted on said carriage for movement at right angles to the movement of said carriage to and from said block machine conveyor means, a pallet handler frame pivotally mounted on said cross movement frame for swinging movement about a vertical axis thereon, a platen vertically reciprocatable on said pallet handler, a pair of oppositely movable probe fingers mounted on said platen adapted to engage vertically disposed facing surfaces on the guide rails of said pallet rack, power means on said platen to oppositely extend and retract said probe fingers, a master potentiometer on said platen adapted to be adjusted by the movement of said probe fingers, an adjustable stop mounted on said carriage having an abutment surface engaging said cross movement frame to limit movement of said cross movement frame away from the block machine conveyors, a slave potentiometer connected to be adjusted by the movement of said stop, a reversible drive motor connected to adjust said stop, and a position control device electrically connected to both of said potentiometers and to said reversible drive motor to control the energization of said reversible drive motor in response to the relative position of said otentiometers.

2. In a pallet handler as set forth in claim 1 wherein said probe fingers are connected to adjust said master potentiometer by means of a rack formed on each of said probe fingers, a common rack pinion engaging both of said rack and rotatably supported on a sliding pinion plate, a rack formed on said pinion plate, a shaft journaled in the platen frame has a gear fixed thereon operatively engaging said rack formed on said pinion plate,

.a potentiometer shaft connected to operate said master potentiometer shaft, a magnetic clutch operable to connect and disconnect said shafts, and a brake interconnectable between said platen frame and said master potentiometer shaft to hold' and release said master potentiometer shaft.

3. In a pallet handler as set forth in claim 1 wherein said probe fingers are connected to actuate said master potentiometer by an element which always moves to the center line of the rack stall independent of the position of the center line of the platen therein so as to adjust said master potentiometer relative to a central position of exact alignment of said center lines by an amount equal to off-set of said center lines, said position control device energizing said reversible drive motor until said slave potentiometer assumes the same position as said master potentiometer to thereby adjust said stop to position the center line of the platen on the center line of said rack stall.

4. In a pallet handler as set forth in claim 3 wherein a pull cylinder device is connected to actuate said master potentiometer to an intermediate position of its travel when said brake is released.

5. In a probing device for a pallet handling machine having a platen movable into and out of a pallet rack between shelf guide rails thereof having spaced facing vertically disposed surfaces adapted to engage the outer edges of a pallet, a probe box fixed on said pallet, a pair of oppositely movable probe fingers slidable in said box at right angles to said guide rails and adapted to move outwardly of said box to engage said vertical facing guide rail surfaces, a fluid pressure cylinder for each of said probe fingers mounted in said box for simultaneously yielding moving said probe fingers in opposite directions, a rack on each of said probe fingers, a pinion plate in said box slidable freely in the same direction as the direction of movement of said probe fingers, a pin fixed to said pinion plate, a rack pinion journaled on said pin and in engagement with the racks formed on said probe fingers, and means to connect said pinion plate to a potentiometer of the control system of said pallet handler.

6. In a probing device for a pallet handling machine as set forth in claim 5, a control limit switch mounted on one of said probe fingers, a trip lug fixed on the other of said probe fingers adapted to engage and actuate said limit switch when the outer ends of said probe fingers have moved farther apart than a predetermined amount to prevent placement of a pallet in a rack where the guide rails are too far apart to hold the pallet.

References Cited in the file of this patent UNITED STATES PATENTS 2,061,495 Woodrufl? Nov. 17, 1936 2,730,251 Schutt Jan. 10, 1956 2,737,303 Held et al. Mar. 6, 1956 2,803,356 Thomas Aug. 20, 1957 

